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photoresistor problem

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hassan ali

Member level 2
May 18, 2010
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hi, sorry for my English

i want a circuit implementation for a pnp phototransistor
note:i am a beginner in this field so i need all components , i prefer a circuit schematic for this circuit.

please help me in short time.

Is this microcontroller relater or have you posted in the wrong category?

What do you want to do exactly,
circuit implementation for a pnp phototransistor
doedn't explain much but in any case you should do something too so don't expect someone else to provide you a ready (homework?) solution.


What would your answer be if I asked for "a circuit for a Nmosfet", would it make sense?
Be more specific what are you trying to do and what are the components involved?
will you control a relay with light or maybe a led or what?


Has anyone seen a pnp phototransistor before?

i want to use a pnp phototransiotr to get the photo light pulse from a device and get then the output from the photo transistor the device is an electronic digital meter produce it's pulses from a led which gives a pulses light for each turn and then i want to take these pulses with a photo transistor.

Has anyone seen a pnp phototransistor before?
I didn't had it at my fingertips, but as far as I know, there once have been Germanium PNP phototransistors. In addition, any Si pnp transistor should have certain light sensitivity, e.g. a metal can package with the cap removed.

It's not clear, which features you expect from the phototransistor circuit. The polarity only matters, if you connect the base terminal, many phototransistor circuits are operating the device like a diode, so PNP or NPN don't make a difference for the circuit.

Any recent types are Si npn, however.

P.S.: An early PNP phototransistor. Transistor Museum Photo Gallery Radio Receptor RR66 Germanium Alloy Junction Photo Transistor
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